The invention relates to pulling means for an airbag module. The invention further relates to an airbag module for a vehicle safety system. The invention moreover relates to a method of manufacturing pulling means for an airbag module.
In the case of modern vehicle safety systems comprising airbag modules it is endeavored to adapt the safety system ever more individually to different parameters of a crash situation. A known and advantageous option consists in the use of pulling means, such as tethers, by the release of which discharge orifices of the airbag are opened or closed. Alternatively, also the airbag geometry can be influenced and/or an additional airbag volume can be released by pulling means of this type. For an actively controlled tether release a tether release means including an activation unit is required, which is also known by the acronym “TAU” (tether activation unit). Airbag modules having activation units of this type are known, for example, from DE 10 2008 028 921 A1 or DE 10 2009 005 771 A1.
The connection between an active discharge orifice at the airbag and the tether release means has been realized so far by an endless cord (loop, eye). Said cord is made of high-strength polyethylene fibers, especially of “Dyneema” fibers, the ends thereof being spliced into a ring by manual operation (soft splice). The previously used cord cannot be stitched directly onto the airbag, however. Therefore it is necessary to additionally stitch a loop of textile airbag fabric onto the airbag wall into which the cord is inserted.
On the other hand, it is known to stitch so called narrow strips, as they are used, for instance, as tensioning strip on a head bag, directly onto the airbag. Narrow strips of this type are flat and have a uniform width and thickness. They are not suited for use in a tether release means including a pyrotechnical activation unit due to the very limited construction space, however. They are too wide for the corridor of approx. 4 mm available in current activation units. A narrower design is not taken into account, because then the rupture load would not be sufficient and the area available for stitching onto the airbag would be too small.